Shower base



FIG. 1 is a top perspective view of a shower base embodying my newdesign;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front plan view thereof;

FIG. 4 is a rear plan view thereof;

FIG. 5 is a left side plan view thereof; and,

FIG. 6 is a right side plan view thereof.

CLAIM The ornamental design for a shower base, as shown and described.